[The] second element [of Amroth] is a derivative from a stem rath- meaning "climb" (whence also the noun rath, which in the NúmenóreanSindarin used in Gondor in the naming of places and persons was applied to all the longer roadways and street[s] of Minas Tirith, nearly all of which were on an incline: so Rath Dínen, the Silent Street, leading down from the Citadel to the Tombs of the Kings).

Unfinished Tales, Part 2, Ch 4, The History of Galadriel and Celeborn: Notes, Note 16